Sampling system

Abstract

A sampling system includes a first sampler which periodically samples an input signal at a fixed sampling period T to output a sequence of samples. A first lowpass filter outputs a sequence of −T/4 phase shifted samples from the sequence of samples. A second lowpass filter outputs a sequence of +T/4 phase shifted samples from the sequence of samples. A second sampler outputs a sequence of secondary samples by alternately taking the −T/4 phase shifted samples supplied by the first lowpass filter and the +T/4 phase shifted samples supplied by the second lowpass filter at,a sampling period that is half the sampling period T, the second sampler doubling the number of the samples output by the first sampler. An interpolation circuit outputs at the sampling period T a sequence of output samples by executing an interpolation of the sequence of secondary samples output by the second sampler, the sequence of output samples having a timing phase synchronized to a given arbitrary clock signal.

1. A sampling method comprising the steps of:
 periodically sampling an input signal at a fixed sampling period T to output a sequence of samples; 
 outputting a sequence of −T/4 phase shifted samples from said sequence of samples; 
 outputting a sequence of +T/4 phase shifted samples from said sequence of samples; 
 outputting a sequence of secondary samples by alternately taking said −T/4 phase shifted samples and said +T/4 phase shifted samples at a sampling period that is half the fixed sampling period T, the number of the samples being thus doubled with the sequence of secondary samples; and 
 outputting at the fixed sampling period T, a sequence of output samples by executing an interpolation of the sequence of secondary samples, the sequence of output samples having a timing phase synchronized to a given arbitrary clock signal. 
 
     
     
       2. The method of  claim 1 , wherein said phase shifted samples are generated by a low pass filter. 
     
     
       3. The method of  claim 1 , wherein said interpolation utilizes Lagrange's interpolation. 
     
     
       4. A sampling method comprising steps of:
 sampling an input signal at a fixed sampling period T to output a sequence of samples; 
 outputting a first sequence of phase shifted samples from said sequence of samples; 
 outputting a second sequence of phase shifted samples from said sequence of samples; 
 outputting a sequence of secondary samples by combining said first and second sequence at a sampling period that is a ratio of sampling period T; and 
 outputting at the fixed sampling period T, a sequence of output samples by executing an interpolation of the sequence of secondary samples, the sequence of output samples having a timing phase synchronized to a given arbitrary clock signal. 
 
     
     
       5. The method of  claim 4 , wherein said phase shifted samples are generated by a low pass filter. 
     
     
       6. The method of  claim 5 , wherein said low pass filter shifts the phase of said first sequence to −T/4. 
     
     
       7. The method of  claim 5 , wherein said low pass filter shifts the phase of said second sequence to +T/4. 
     
     
       8. The method of  claim 4 , wherein said combining of said first and second sequence occurs by alternating said first and second sequence. 
     
     
       9. The method of  claim 4 , wherein said interpolation utilizes Lagrange's interpolation.